This invention relates to an induction system for an engine and more particularly to an improved induction system for a fuel-injected outboard motor.
In the interest of conserving fuel resources and protecting the atmosphere, it has been the practice to employ fuel injection systems for internal combustion engines. Fuel injection systems are utilized because they offer more accurate control over the fuel flow for a wide variety of running conditions. These systems are employed with many applications for internal combustion engines, including outboard motors.
Although fuel injectors offer good control of fuel economy and exhaust emission, there are some running conditions wherein the present induction systems can be improved. For example, with an outboard motor the engine is frequently operated for a long period of time at very low speeds. For example, when trolling the engine may actually be run for long periods of time at speeds that are even less than idle speed.
With most forms of fuel injection, it is the practice to control the amount of pressure of the fuel supplied to the fuel injector by utilizing a pressure relief valve which bypasses fuel back to the fuel system from the fuel injector. When operating at these low speeds such as they are encountered during trolling, more fuel is actually bypassed than is consumed. The continuous recirculation of the large quantity of fuel, particularly in proximity to the engine, can give rise to increase in the temperature of the fuel. This can cause vapor bubbles to form in the fuel and can upset the fuel air ratio. These problems are particularly acute due to the compact nature of outboard motors and the fact that the engine is normally surrounded rather closely by a surrounding protective cowling.
Also, it is normally the practice to employ an electrically operated fuel injector and this may include one or more solenoids that are electrically operated and which control the injection. The electrical solenoid adds further heat to the system which can further heat the fuel and cause the problems aforenoted.
It is, therefore, a principal object to this invention to provide an improved induction system for an engine.
It is a further object of this invention to provide an improved induction system for a fuel injected outboard motor.
It is yet a further object of this invention to provide an induction system for a fuel injected outboard motor wherein the induction system is constructed and arranged in such a way as to provide a cooling operation for the fuel injectors so as to avoid the problems as aforenoted.